Fabricating objects with integral and contoured rear projection

ABSTRACT

A method for manufacturing a three dimensional (3D) object with a rear projection (RP) surface. The method includes providing a rapid prototyping machine, such as a stereolithography machine, with input material, such as a white photopolymer resin. The method includes providing a digital prototyping file, which defines thin, separately grown layers of a digital representation of the 3D object, to a computer control system. With the computer control system, the rapid prototyping machine is operated to form a 3D object using the input material and the digital prototyping file. As a result, the 3D object includes an RP element, which behaves as an RP substrate or surface. A structural portion of the 3D model has a first thickness and an RP portion has a second thickness that is less than the first thickness such that it is translucent to provide an RP element integrally formed with an adjacent structural element.

BACKGROUND

1. Field of the Description

The present invention relates, in general, to techniques for forming acontoured or non-planar substrates or structure that can be used forrear projection (RP) such as the eyes or other portions of ananimatronic or robotic character, and, more particularly, to a method offabricating an object with a rear projection (RP) substrate or RP screenelement that may be contoured or dimensional and is integrally formedwith an adjacent structural substrate(s) or a non-projecting element(s)of the object. For example, the method may be used to form an RP screenelement that provide animated eyes of an animatronic character orcreature when light and/or images are projected upon rear surfaces ofthe RP screen element.

2. Relevant Background

There are many applications where it is useful to provide a rearprojection or RP screen within an assembled product. For example, themeparks may provide animatronic creatures and characters within in showportions of theme rides or on floats of a parade. To make the creaturesand characters come to life it is desirable for their eyes and theirother body parts to move.

While it is useful to use mechanical assemblies to move many body parts,robotic-type eyes may seem unrealistic and “give away” the roboticnature of the creature or character. Many designers of animatronics orrobotics have, as a result, begun to animate or bring life to eyesthrough the use of rear projection. In use, an animatronic character'seyes can be provided with one or more RP elements and one or moreprojectors that project still or video images displaying still or movingeyes. The video projection may be timed or synchronized, for example,with the moving of the head, mouth, and so on or to follow a personobserving the character to effectively bring the character to life.

The RP element or substrate can limit the quality of the resultingprojection in a number of ways and fabrication of objects or characterswith RP substrates has presented difficulties that have not yet beenfully addressed. Presently, the fabrication process of such a characterinvolves forming a support structure for the RP elements and thenattaching the RP elements. The support structure, for example, may beall or a portion of a character's face or head, and openings or holeswill be provided or later cut out of this face or head to provide aplace to attach the RP elements. The RP elements are separately formedand then carefully applied to the face or head, and then the projectoris positioned within the face or head for use in projecting on the rearsurface of the RP elements.

While the above steps may be labor intensive so that they are relativelycostly and time consuming, more significant problems with fabrication ofthe object with RP substrates typically arise in the production of theRP substrates themselves. The RP substrates are typically arcuate orcontoured in overall shape (e.g., non-planar) and also have to be formedwith particular optical qualities to provide a good RP screen.

To this end, the RP substrate is typically formed using a multi-stepprocess that includes first forming a clear or substantially transparentbase substrate or layer such as through vacuum forming with atranslucent to transparent plastic. The base substrate typically willhave at least one curved or non-planar surface (e.g., a portion of asphere) or may be thought of as a three-dimensional (3D) surface, butthe substrate also preferably has uniform thickness to provide uniformtransmission of light. Unfortunately, vacuum forming often provides aproduct that has varying thickness, and this leads to repeated attempts(or a trial and error-type process) to generate a more uniform thicknessbase substrate, which increases the time and cost to provide each basesubstrate. In a typical run, it is has been found that up to 80 percentof the parts have to be rejected due to unacceptable variance in thesubstrate thickness.

Additional problems arise in the final processing of the base substrateto provide the RP substrate. A typical next step is to apply an RPcoating onto the rear or inner surface of the base substrate. The RPcoating acts to provide the desired optical properties to the RPsubstrate such that light providing still and video images areeffectively projected via the RP substrate (similar to an RP screen in amovie theater). The RP coatings presently in use are very expensive(e.g., up to $600/gallon), and it may require several coatings toachieve a desired result such as particular optical qualities. Further,the RP coating materials are typically toxic and special sprayingfacilities or equipment may be required for their use.

The spraying or application process can be complex and challenging, andit often can result in rejected parts due to non-uniformity or flaws inthe RP coating layer (e.g., one drip of the RP coating in one of the twoor more applications can produce an undesirable RP substrate). Thesechallenges have typically required that manufacturers ofanimatronic/robotic characters or other objects with RP substrates sendthe base substrates out to another company (or division) for applicationof the RP coating, which further adds to the fabrication timeline andincreases overall costs.

Hence, there remains a need for an improved method of fabricating RPsubstrates or elements for use in objects or devices that make use of RPsystems to display imagery. Preferably, such a method would reduce thetime and/or cost required to fabricate the RP substrate and, therefore,the object or RP assembly that includes the RP substrates. The methodalso may be selected or designed to better provide uniform opticalqualities across or throughout each RP substrate produced by the method(e.g., a more uniform thickness of material(s)).

SUMMARY

To address the above and other needs, the present description describesa method of fabricating a 3D object, such an animatronic head or thelike, that includes one or more rear projection (RP) surfaces orsubstrates. Significantly, the method uses a rapid prototyping machineto concurrently form the RP substrate with its adjacent or surroundingsupport elements (e.g., a face may be formed with the eyes providing theRP substrate and the forehead, cheeks, and nose providing structuralsupport elements for the RP substrate). For example, the method mayinclude use of a stereolithography machine that is controlled by acomputer control system using an input file to define the thin layers ofa digital 3D model or computer graphic of the 3D object to sequentiallygrow or print. The layers are printed or grown using lasers (or otherdevices) to selectively cure a 2D pattern or slice of the 3D model in avat or container containing a UV-curable photopolymer resin (or liquidplastic).

In one implementation, the photopolymer is chosen such that when it iscured it provides a rigid, translucent, white plastic, and the opacityor translucence is selected such that the RP substrate has the opticalcharacteristics or qualities of an RP screen. The 3D model is modifiedor generated such that the RP portions are assigned a thickness that istypically much less than the adjacent/surrounding structural portions soas to provide the desired RP screen-like optical qualities (e.g., 50percent or less of the thickness of the structural/support portions Whenthese are about 1/16-inch thick and the input/feed material used in theprocess is a white photopolymer such as ACCURA 55 available from 3DSystems Corporation, Rock Hill, S.C., USA or the like). In this manner,rapid prototyping is used to concurrently and integrally form thestructural and RP portions of the 3D object, and the RP portionstypically will have uniform thickness and not require any additionalcoatings or treatments to act as RP screens when projected upon by aprojector.

More particularly, a method is provided for manufacturing a threedimensional (3D) object with a rear projection (RP) screen or surface.The method includes providing a rapid prototyping machine and thensupplying a volume of input material to the rapid prototyping machine.The method further includes providing a digital prototyping file to acomputer control system configured to control the rapid prototypingmachine. With the computer control system, the rapid prototyping machineis operated to form a 3D object using the input material based upon thedigital prototyping file. As a result or output of the manufacturingmethod, the 3D object includes an RP element with a rear surface and afront surface. The RP element is adapted for displaying (e.g., imagerythat animates the RP element) via the front surface when light isprojected upon the rear surface.

In some embodiments of the method, the rapid prototyping machine is astereolithography machine. In such embodiments, the digital prototypingfile may define a plurality of layers of a 3D model (e.g., down to 0.020inches thick or less) that are separately formed (grown, cured, printed,or the like) by the stereolithography machine. The 3D model may includean RP portion corresponding with the RP element and a structural portioncorresponding to a structural element with at least one side integrallyand concurrently formed with an adjoining side of the RP element duringthe operating step. In such cases, the structural portion of the 3Dmodel is associated with a first thickness and the RP portion of the 3Dmodel is associated with a second thickness that is less than the firstthickness, whereby the RP element formed by the stereography machine ismore transmissive of light than the structural element. For example, thefirst thickness is greater than about 1/16 inches and the secondthickness is less than about 1/32 inches. In some implementations, theinput material is a UV-curable photopolymer resin that may be selectedto provide a translucent white plastic in the operating step.

According to another aspect of the method, the 3D object furtherincludes a structural element with at least one adjoining edge with theRP element to support the RP element within the 3D object. In such anembodiment, the structural element is formed at least partiallyconcurrently with the RP element during the operating step. In suchcases, the method may further include treating the structural elementsuch that the structural element is less transmissive of light than theRP element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block or schematic diagram of a fabricationsystem for use according to methods of the present description togenerate a 3D object or part with an integrally formed RP substrate orportion using rapid prototyping;

FIG. 2 illustrates a front perspective view of an assembly or object,such as an animatronic or robotic character, that includes an RPsubstrate formed using the techniques and systems described herein suchas the fabrication system of FIG. 1;

FIG. 3 is partial sectional view of the assembly of FIG. 2 taken at line3-3 showing that the RP element or substrate is formed integrally withadjacent structural members or portions and is formed to have adifferent thickness and to not require additional coating/painting;

FIG. 4 is a rear perspective view with a rear cover/cap removed to showinternal components of the assembly/object of FIGS. 2 an 3 and also withseveral components or features shown in functional block or schematicformat; and

FIG. 5 illustrates with a flow diagram one exemplary method offabricating an assembly or object, such as that of FIGS. 2-4, with a RPsubstrate or portion using rapid prototyping techniques.

DETAILED DESCRIPTION

Briefly, the following description teaches a method of fabricating a 3Dobject or part that includes a rear projection (RP) portion or elementand, in many embodiments, also includes a structural or support portionor element adjacent and/or surrounding the RP element. In thefabricating method, rapid prototyping such as stereolithogaphy isutilized to grow or print the RP element such that it may be integrallyformed with the surrounding and supporting structural element(s). Inother words, a 3D part or object is formed that includes both the RPelement and one or more structural elements interconnected with one ormore edges/sides of the RP element.

The rapid prototyping is performed with an input or feed material ormaterials that provide the desired optical qualities in the RP element.In this way, additional processing such as applying an RP coating aregenerally not required to achieve a useful RP screen/surface in the 3Dpart. Further, the RP element can be formed integrally with the adjacentstructural elements/portions but be much thinner or have smallerthickness than the structural elements. The prototyping input or feedmaterial typically provides a translucent RP element that is useful forrear projection applications, and the structural elements may be paintedor coated in a later step so as to make these portions opaque to thelight from a rear-positioned projection targeting the rear or innersurface of the RP element(s).

The 3D part or object is then used in the final assembly of a RPassembly or system that typically will include at least one projectoroperable to project onto the rear or inner surface of the RP element.The RP assembly may further include an actuator mechanism(s) foractuating animatronic or robotic features of the RP assembly (e.g., tomove a mouth) and a controller for operating the projector(s) and/or theactuator mechanisms (e.g., in a synchronized manner to animate the RPelements with the animatronic or robotic features).

FIG. 1 illustrates a fabrication assembly or system 100 for use inproducing 3D objects or parts 160 that include an RP portion or element164. The RP portion 164 typically has at least one curved or otherwisenon-planar segment and is configured to be useful in receiving images(such as video or still imagery) on one side (e.g., the back, rear, orinner surface) and to, in response, display the projected image on theopposite side (e.g., the front or outer surface). The 3D object or part160 typically will also include a structural portion or element(s) 162,and the structural or support element 162 may be adjacent to one or moresides/edges of the RP element 164 or surrounding the entire RP element164. The RP element 164 may also be formed so as to be integral with thestructural element 162, e.g., the two elements 162, 164 may be formed ina single process so that additional bonding or attachments steps are notrequired to create the 3D object 160.

To this end, the system 100 includes a rapid prototyping machine ordevice 110 that produces or provides as its output 150 the 3D object 160with the RP portion 164 integrally formed with the structural/supportportion 162. Significantly, the inventor recognized that thedifficulties with trying to form RP substrates that are later glued to astructural base (e.g., RP eyes to a face with holes for receiving the RPeyes) could be addressed by fabricating the structural and RP elements162, 164 in a single process.

Further, the system 100 includes a material supply 120 because theinventor understood that if the input materials 125 provided to therapid prototyping machine 110 are properly selected to provide usefuloptical properties of an RP substrate in RP element 164 then additionalcoatings and processing are not required. Additionally, the inventorrecognized that the rapid prototyping machine 110 could be chosen suchthat it may be run/controller to produce an RP portion 164 of the 3Dobject/part 160 that is thinner than the structural portion 162. Thisallows each element 162, 164 to perform its design function (e.g., oneacting to transmit light as an RP substrate and one acting to supportthe RP substrate and otherwise provide structural integrity to the 3Dobject).

A wide variety of rapid prototyping machines/devices exist and may beutilized for machine 110 to provide the output 150 described herein suchas non-photopolymer-based devices such as fusion deposition modeling,laser sintering, and an inkjet system. However, in one useful example ofsystem 100, the rapid prototyping machine 110 takes the form of astereolithograpy device (sometimes also called solid-statestereolithography or 3D printing device). In general, stereolithographyis an additive manufacturing process using input materials 125 in theform of a liquid UV or otherwise-curable photopolymer resin (or liquidplastic). A laser (e.g., a UV laser) prints or builds/grows 3D parts orobjects one thin layer at a time. On each layer of the 3D object 160,the laser beam of the machine 110 traces a part cross-sectional patternon the surface of the liquid resin 125. Exposure to the UV laser lightcures or solidifies the material 125 in the pattern traced on theresin/liquid plastic and adheres it to the layer immediately below orpreviously-formed layer.

After a layer is traced or grown, a platform supporting the 3D objectbeing formed is lowered by a single layer thickness (e.g., 0.002 to0.020 inches or the like). Then, a resin/liquid plastic-filled bladesweeps across the part cross section to coat it with fresh material 125.On this new liquid, the next layer of the 3D object 160 is traced withthe laser and adheres to the prior layer. This process is repeated untila complete 3D object/part 160 may be provided as the output 150 of themachine 110. Supports or supporting materials may be provided by themachine 110 to maintain the structural integrity to prevent deformationduring gravity and/or from movement with the refill blade. Also,additional processing such as cleaning of excess resin and/or curing ina UV oven or the like may be performed for some stereolithographymachines 110.

The system 100 further includes a controller or computer control system130 that acts to selectively provide control signals 149 to the rapidprototyping machine 110 to operate to create the output 150. Forexample, the controller/computer control system 130 may act to direct alaser across the surface of a polymerizable plastic in a pattern definedby a prototyping file 148 in its memory 132. This converts the inputliquid materials 125 into a solid on a point-by-point basis. The laserconverts to solid plastic all the points in one layer that are neededfor this layer of a prototyping file 148 (or a layer of model 140) so asto produce a two dimensional lithograph. Then, the control signals 149may instruct the machine 110 to drop the platform supporting the objectbeing gown a small increment and then grow/print a next layer. Once alllayers are converted to solid, the complete 3D object or part 160 can belifted from the liquid plastic/resin vat as output 150 of the machine110.

The 3D object/part 160 is a complete model or exact replica of acomputer graphic or 3D model. Specifically, the controller 130 may takeas input a computer graphic or digital 3D model file 140 of an objectthat is to be grown/printed as the 3D object/part 160. For example, acomputer modeling program such as a computer aided design (CAD) programmay be used to create the 3D model file 140 of the object, and the modelfile 140 may define nearly any 3D structure (as long as it hasstructural integrity during the building/growing process of machine110). For example, a 3D scan of an object (such as external surfaces ofa character/creature or their head/face) may be taken and used as astarting point for the 3D model file 140.

One unique aspect of the 3D object 160 is that it can include materialof two or more thicknesses so that one may provide desired opticalcharacteristics of an RP screen (i.e., elements 164) while the other,thicker portions may be stronger (i.e., support/structural elements162). Hence, the 3D model of the object 140 may define one or moreportions 142 that are used as structural components of the 3D object 160(structural portion 162), and these may have thickness 143 assigned tothem such as 1/16 to ⅛-inch or more thick. Depending on the polymer usedas the input materials 125, this may be too thick for use as an RPscreen.

As shown, though, the 3D model 140 further defines one or more portions146 that are used as the RP components of 3D object (RP portions 164).These RP portions 146 of the digital 3D model 140 are assigned a secondthickness 147 that is less than the thickness 143 of the structuralportions 142. For example, some polymers or liquid plastics used as theinput 125 may provide excellent optical qualities (e.g., desiredtransmission of light from a front surface when the light is projectedon an opposite rear surface) when at thicknesses of less than 1/16inches such as down to 1/32-inch or less in thickness (e.g., a range ofabout 0 to 1/16-inches may be used with some prototypes tested at about1/32 inches). The thickness 147 of the RP portions 146 is set to beuniform throughout the RP portion 146, which is an advantage over priorRP substrates formed using vacuum forming as vacuum forming often led tovarying thicknesses. The thickness 147 will vary based on a desiredresult and the intended use of the RP substrate 164 (e.g., how dark orlight the use environment will be, the brightness of the projectors thatwill rear project onto the RP portion 164, and so on).

The controller 132 may then use software (not shown) to chop or separatethe 3D model 140 into thin layers (e.g., 5 to 10 millimeters or thelike) or cross sectional patterns that are provided in prototyping file148 in memory 132. The control signals 149 are then generated based onthe file 148 to paint or print the 3D object 160 layer-by-layer toprovide a 3D replica or model of the object/graphic defined in 3D modelfile 140. Preferably, the software/programs run by the CPU/processors ofcontroller 130 allow a user to set and then later reset which portionsof the 3D model 140 will be used as the structural and RP portions 142,146 and to set and reset the thicknesses 143, 147. Typically, the model140 will define a 3D model/shape, and the thicknesses 143, 147 are setas offset distances from the outside surfaces of the 3D model/shape.Such functionality allows a prototype to be grown by machine 110 andtested, and, based on the test, to adjust thicknesses 143, 147 toachieve better or different results (e.g., decrease or increasethickness 147 of the RP portion 146 to get a desired RP substrate withRP element 164 with a particular material 125). This adjustment functionalso allows the user to try differing input materials 125 to get betterfunctionality from the RP portion/element 164 of the finished 3Dobject/part 160.

Many different input materials 125 may be used in system 100 to achieveuseful results with the RP element 164 (as well as provide adequatestructural integrity and strength in portion 162). Generally, anyplastic or polymer may be used that functions as an RP substrate such asat thicknesses 147 of less than about 1/16 inch. This would include allor nearly all common photopolymers used in stereolithography such as anepoxy-based resin or hybrid. In one tested implementation of system 100,the material supply 120 provided input materials 125 in the form of aliquid plastic that, when hardened, provided a white plastic (e.g., awhite, molded ABS-like part), and it provided excellent RP substrateresults at thicknesses of less than about 1/32 inches. Specifically, theinput material 125 used in this test of a stereography machine formachine 110 was ACCURA® 55 plastic available from 3D SystemsCorporation, Rock Hill, S.C., USA. However, it is likely that many otherstereolithography (SL) materials may also be useful such as ACCURA® 25or other SL materials from 3D Systems Corporation (or otherdistributors/manufacturers) or other SL materials. Further, good resultshave been achieved with plastics that have a white appearance, but otherimplementations may use a different color such as gray, tan, or anothercolor (but typically not transparent/clear to achieve desired RP opticalqualities).

FIG. 2 illustrates a front perspective view of an assembly or object 200(e.g., an animatronic or robotic character) that includes an RPsubstrate formed using the techniques and systems described herein(e.g., the fabrication system of FIG. 1). The object 200 includes a bodyor support element 210 that may be formed as described above using arapid prototyping machine, and the support element 210 may be formed tobe relatively thick so as to provide structural strength and integrityfor the object 200.

The support element 210 is shown to be a dimensional component(non-planar) with curved and irregular surfaces such as may beassociated with a head and face of a human, an animal, or a character.The object 200, in this case, is an animatronic character, and theobject 200 includes a positionable or actuable member 214 (e.g., a mouthor lower jaw of a mouth (as shown)) that can be selective moved up anddown as shown with arrow 215. The support element 210 is formed of amaterial such as a plastic that can be formed using rapid prototypingtechniques and is rigid and stiff to support the moving 215 member 214.For example, the support element 210 may be formed of a plastic that isat least about 1/16-inch thick such as the plastics that result fromcuring photopolymer resins used in an SL machine.

Significantly, the object 200 is further animated through the use of arear projector (e.g., shown at 482 in FIG. 4). Specifically, the object200 includes an RP element or substrate 220 in the form of a pair ofeyes provided as a single unit or piece. The front or outward facingsurface or side 225 is Shown to be displaying images (e.g., portions ofthe eyes of the creature simulated by Object 200) as the object 200 isoperated. During such operation, a rear projector 482 is operated toproject light or an image stream onto a rear or inward face surface orside of the RP substrate 220 opposite the front surface 225.

The RP substrate 220 is formed of a material (such as white plastic)that is useful for providing an RP substrate (e.g., adequate opacity tonot simply transmit light through the front surface 225) and also at arelatively small thickness to effectively transmit the images from thefront surface 225 (e.g., at least translucent). For example, a whiteplastic formed using a UV-curable photopolymer and an SL machine may beused at a thickness of less than about 1/16 inches (such as 1/32-inchthick or thinner).

As discussed above, the use of rapid prototyping techniques toconcurrently form the support element 210 and RP element 220 allows theRP element 220 to be formed integrally with the support element 210. Asa result, there are no additional fabrication steps to cut a hole/gapfor receiving the RP element 220, no steps required for separatelyfabricating the RP element 220, and no additional steps for bonding theRP element 220 to the support element 210. After stereolithography orother rapid prototype fabrication, the RP element 220 is integrallymated/joined with (or has bonded sides/edges with) the adjacent or, inthis case, surrounding portions of the support element 210.

Further, the use of a thin white (or other color) plastic for RP element220 typically alleviates the need for applying an RP or other coating tothe rear surface of the RP element 220 (as was required when an RPsubstrate was vacuum formed from clear plastic). The use of rapidprototyping as described herein allows the RP element 220 to be formedof a much smaller thickness (such as about 50 percent or less) comparedwith the surrounding and supporting structural element 210.

FIG. 3 illustrates a partial sectional view of the object or animatroniccharacter 200. It shows a side view of the RP element or substrate 220with its front surface or side 225 and a rear surface or side 328 thatwould face a rear projector (projector 482 in FIG. 4). FIG. 3 also showsa side view of adjoining portions or segments of the support element210, and it can be seen that the support element 210 is mated with orintegrally formed with the sides or edges of the RP element 220 tophysically support or retain the RP element 220 within the object 200.While the RP element 220 typically requires no further RP coating orother treatments, the support element 220 may be unacceptabletranslucent or be a color (such as white) that is undesirable for theobject 200. To provide a different color and/or to make the supportelement 210 more or fully opaque, a layer of paint 370 or a similarmaterial/coating may be applied on the outer surface as shown or, insome cases, on the inner side/surface of the support element 210.

As shown, the support element 210 has a first thickness, t₁, while thesupported RP element 220 has a second thickness, t₂ (both measured froma front/outer side to a rear/inner side). The first thickness, t₁, ischosen for structural/strength reasons while the adjacent or surroundedRP element 220 has a thickness, t₂, that is chosen mainly to provide aneffective RP substrate (based on the particular material used to formthe RP element 220). The use of rapid prototyping techniques such asstereolithography allows these two thicknesses to be provided with anintegral or unitary (one piece) part, and the variance can be quitelarge. For example, the RP element 220 may have a thickness, t₂, that isless than about one half that of the support element 210 such as lessthan 1/32 inch when the support element is 1/16 inches or more thick. Ofcourse, other thicknesses may be used to suit a particularprojection/display effect desired, a display environment (how light ordark is the display environment), and so on. The particular valuesprovided have, however, proven effective when the rapid prototypingmachine is an SL machine and the liquid feed/input material is ACCURA®55 (a white, UV-curable photopolymer).

FIG. 4 illustrates a partial rear or back view of the object 200 withseveral components shown in schematic or functional block format. Asshown, the object 200 includes that structural/support element 210 thatsupports the integrally-formed RP substrate or element 220 (e.g., theanimatronic character's eyes), with the rear or back surface/side 328 ofthe RP element 220 facing inward into the object 200. The object 200also includes the movable/positional member 214 pivotally supported uponthe support/structural element 210.

A controller or computer control system 480 is provided that selectivelyoperates a projector 482 to project light or an image stream as shown at483 onto the rear or back surface 328 of the RP element 220. Thisresults in images being displayed upon the front surface 225 of the RPelement 220 as shown in FIG. 2, and the projected images 483 may bestill images or, more commonly, are video images (e.g., moving eyes inthis example). The projector 482 is not limiting of the invention, andit may be nearly any projector (such as an LED or other micro/picoprojector useful for providing a 100 to 1000 or more lumen output ofstill or video images that may be black and white or, more typically,color). The controller 480 may synchronize operation of projector(s) 482and/or select the content 483 shown by projector(s) 482 based onoperation of robotics actuator(s) 484. The robotics actuator 484 isinterconnected with positioning mechanism(s) 486 so as to selectively(e.g., in response to control signals from controller 480) move orposition the positionable member 214.

FIG. 5 illustrates a method 500 of fabricating an object (such as object160 or 200) that includes an RP substrate or element (such as RP element164 or 220). The method 500 starts at 505 such as with selecting anobject such as an animatronic or robotic character that will be thetarget of the method 500 and for which its eyes or another portion willbe animated or otherwise used as an RP screen. At 510, the methodincludes generating a 3D model of the object. For example, a 3D scanningtechnique may be used to generate a 3D model or computer graphic file ofthe exterior surfaces of a 3D object (non-planar object) such as a modelof a head or face of a character or a human face/head. Alternatively, a3D model may be generated or otherwise provided by a CAD program (orother software program), as nearly any 3D model may be used as input tothe method 500 and used to generate a part or model using rapidprototyping such as stereolithography.

At step 520, a user of the CAD or other program being used to generatedthe 3D model acts to select one or more portions of the 3D model for useas RP substrates (or RP screen components). For example, a head may bemodeled and the entire head may be used as the RP substrate. In othercases, a portion of the face (or a subset of the 3D model) is used asthe RP substrate such as the eyes as shown in FIGS. 2-4. In step 530,the method includes choosing or setting which rapid prototypingtechnique will be used (stereolithography or another technique) and,then, which of the many available materials for that technique will beused to form both the structural and RP substrates or elements. In theabove example, a stereolithography machine was chosen and used to formthe 3D object, and a white UV-curable photopolymer resin (or liquidplastic) was used as the feed stock or input materials for the SLmachine. In other cases, though, a gray or tan liquid plastic may beused or another white photopolymer may be used than the one discussedabove (ACCURA® 55).

Based on the optical and structural characteristics of this selectedinput or feed material, step 540 involves setting thicknesses of the RPelement(s) and the structural element(s). Typically, the RP elementswill be much thinner than the adjacent or surrounding structuralelements, but this is not required to practice the invention (such aswhen the thickness for the RP elements for the particular material andintended use of the 3D object are adequate to provide structuralintegrity for the structural/support elements). For example, thethickness (as measured from the outer surfaces defined by the 3D model)may be set at a value equal to or less than about 1/32 inches for the RPelements and at a value equal to or greater than about 1/16 inches forthe structural elements (such as when a white plastic is used togrow/form the 3D object in the rapid prototyping machine). The thicknessof the RP substrate generally may vary with factors such as thetranslucence of (or how transmissive to light) the plastic (or othermaterial) and such as the display effect trying to be achieved in the 3Dobject/assembly. A more translucent material may require more thicknessand vice versa (e.g., a gray plastic may be set to have smallerthickness than a white plastic).

At step 550, a rapid prototyping file is generated—such as by theprototyping machines software provided in its controller—from the 3 dmodel of the object (including the differing thicknesses). Forstereolithography, this may involve software operating to divide the 3Dmodel into a plurality of very thin layers that can be separatelygrown/printed to form a 3D object/part based on the digital 3D model. Atstep 560, rapid prototyping (such as via use of an SL machine) isperformed with the selected feed or input material and the rapidprototyping input file to form a 3D object/part that includes both thestructural elements and the defined/selected RP substrates/elements.This step may also include providing supports/braces to support thesidewalls of the 3D object as it is being built, and then the removal ofthese supports/braces and, in some cases, cleaning of the 3D object toremove excess material. Further, step 560 may include post-formationsteps such as additional curing of the overall 3D object/part.

At step 570, the structural portions or elements may be painted orotherwise treated to achieve a desired look and/or to make theseelements/portions less transmissive or even opaque to light (e.g., thelight of the rear-mounted or positioned projector when it projects onthe RP substrate/element(s)). At step 580, the method 500 continues withassembling (as necessary or desired) the 3D object such as by providingone or more projectors that are focused upon the rear or back surface ofthe RP elements, by providing and connecting robotic or animatronicassemblies/components, by mounting part/object grown in rapidprototyping onto other support components/frames (e.g., mounting a headonto a body or the like), and so on to form a complete 3D object orassembly in which rear projecting may be performed on the RPsubstrate/element to display images (e.g., animate a portion of the 3Dobject or assembly during its use). At 590, the method 500 ends, and itmay be repeated to create different objects using differing 3D modelsand/or differing materials and/or differing thicknesses for the RPsubstrate/element or structural components.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the present disclosurehas been made only by way of example, and that numerous changes in thecombination and arrangement of parts can be resorted to by those skilledin the art without departing from the spirit and scope of the invention,as hereinafter claimed. The use of rapid prototyping techniques such asstereolithography greatly simplifies the fabrication of a 3Dobject/assembly with an RP substrate/element (e.g., can all or most bedone in one operation rather than multiple processes as required whenthe substrates are formed separately using vacuum forming or the like).

The methods taught herein significantly improve accuracy and reliabilityof the fabrication process, too. For example, the digital 3D model (withthicknesses of structural and adjacent/surrounded RP substrates defined)and prototyping input file (with the thin layers defined) can be used toprovide nearly complete control over the thickness and shape of the 3Dobject with consistency of the material, which leads to consistency oftransparency/opacity throughout the 3D object including in the RPsubstrate.

One drawback or feature that had previously taught away from the use ofstereolithography for forming a rear projection surface is the linesthat may seen or formed in the RP substrate. The RP substrate preferablyis very smooth (as is achieved with vacuum forming), but the use ofstereolithography results in “lines” across the surface of the RPsubstrate as the substrate is grown one thin layer at a time. The sizeof these lines depends on the resolution of the particularstereolithography machine, and the inventor has tested machines withresolutions of about 0.020 inches per layer. This SL machine provide RPsubstrates with layers or “lines” that were fine enough to achieve avery useful rear projection surface/screen (again, using a whitephotopolymer such as ACCURA® 55 or the like). It is believed that higherresolution machines are desirable and likely will be available in thecorning years, which will improve the results achievable with the methodtaught herein making it even more desirable for widespreadimplementation.

In some embodiments, the feed or input material used in the rapidprototyping may simply be a white or other color plastic/polymer.However, in other cases, it may useful to provide an additive to obtainenhanced optical properties and rear projection results. For example,the RP coating materials commonly used to coat the back surface of avacuum formed, transparent part to provide an RP substrate may be addedto the photopolymer to provide an RP substrate using stereolithographythat is more desirable as an RP substrate (e.g., provides a brighterdisplay with the same projector). Also, it may be useful to choose astronger input or feed material to allow the RP substrate to be thinner(which also may provide a brighter output), e.g., a thickness of 1/64 to1/32 inches may be achieved and useful in some cases.

1. A method of manufacturing a three dimensional (3D) object with a rearprojection (RP) screen or surface, comprising: providing a rapidprototyping machine; supplying a volume of input material to the rapidprototyping machine; providing a digital prototyping file to a computercontrol system configured to control the rapid prototyping machine; andwith the computer control system, operating the rapid prototypingmachine to form a 3D object using the input material based upon thedigital prototyping file, wherein the 3D object includes an RP elementwith a rear surface and a front surface, the RP element adapted fordisplaying via the front surface when light is projected upon the rearsurface.
 2. The method of claim 1, wherein the rapid prototyping machinecomprises a stereolithography machine and wherein the digitalprototyping file defines a plurality of layers of a 3D model that areseparately formed by the stereolithography machine.
 3. The method ofclaim 2, wherein the 3D model includes an RP portion corresponding withthe RP element and further includes a structural portion correspondingto a structural element with at least one side integrally andconcurrently formed with an adjoining side of the RP element during theoperating step.
 4. The method of claim 3, wherein the structural portionof the 3D model is associated with a first thickness and the RP portionof the 3D model is associated with a second thickness that is less thanthe first thickness, whereby the RP element formed by the stereographymachine is more transmissive of light than the structural element. 5.The method of claim 4, wherein the first thickness is greater than about1/16 inches and the second thickness is less than about 1/32 inches. 6.The method of claim 2, wherein the input material is a UV-curablephotopolymer resin.
 7. The method of claim 6, wherein the UV-curablephotopolymer is selected to provide a translucent white plastic in theoperating step.
 8. The method of claim 1, wherein the 3D object furtherincludes a structural element with at least one adjoining edge with theRP element to support the RP element within the 3D object, wherein thestructural element is formed at least partially concurrently with the RPelement during the operating step, and the method further includingtreating the structural element such that the structural element is lesstransmissive of light than the RP element.
 9. A rear projection (RP)assembly, comprising: a non-planar RP substrate with a front surface anda rear surface; a support element with at least one side abutting atleast one side of the RP substrate, wherein the RP substrate and thesupport element are formed as a unitary part and wherein the RPsubstrate is at least partially transmissive of light striking the rearsurface and the support element is substantially opaque; and a projectorprojecting content onto the rear surface of the RP substrate.
 10. The RPassembly of claim 9, wherein the RP substrate and the support elementare concurrently formed of a plastic using rapid prototyping.
 11. The RPassembly of claim 10, wherein the rapid prototyping compriseslayer-by-layer forming of the RP substrate with each layer being lessthan about 0.020 inches thick and the support element using asterography machine selectively curing a photopolymer resin.
 12. The RPassembly of claim 11, wherein the photopolymer resin comprises awhite-colored plastic liquid.
 13. The RP assembly of claim 9, whereinthe support element and the RP substrate comprise a white plastic andwherein the support element has a first thickness and the RP substratehas a second thickness less than the first thickness.
 14. The RPassembly of claim 13, wherein the first thickness is at least about 1/16inches and the second thickness is less than about 1/32 inches.
 15. Amethod of fabricating a 3D object with a portion adapted for use as arear projection (RP) screen, comprising: generating a digital 3D modelof an object; identifying a first portion of the 3D model as an RPsubstrate and a second portion adjacent the first portion as astructural support; setting a first thickness for the first portion anda second thickness greater than the first thickness for the secondportion; and with a rapid prototyping machine, performing rapidprototyping using the 3D model to at least partially concurrently form a3D object including an RP element with the first thickness and astructural element with the second thickness.
 16. The method of claim15, wherein the RP element and the structural element are integrallyformed of a translucent white plastic.
 17. The method of claim 16,wherein the rapid prototyping machine comprises a 3D printing machineoperating during the performing step to grow the 3D objectlayer-by-layer from a photopolymer resin.
 18. The method of claim 17,wherein the first thickness is less than about 1/32 inches.
 19. Themethod of claim 17, wherein each layer grown by the 3D printing machineis less than about 0.020 inches thick and wherein the RP element has atleast one arcuate-shaped portion and has a substantially uniformthickness across the arcuate-shaped portion.
 20. The method of claim 15,further comprising providing a projector projecting video content upon afirst surface of the RP element, wherein the RP element is at leastpartially transmissive of light whereby images associated with thecontent are displayed on a second surface of the RP element opposite thefirst surface.